1. Field of the Invention
The present invention is related to an improved structure of an alternately inflated/deflated air bed, and especially to an improvement that is applied in clinical medicine to help a patient lying on a bed for a long period to avoid obtaining pressure sores and decubitus ulcers by alternately changing contact points of his body with the bed to obtain adequate ventilation of the skin of his body. The air bed is made by an arrangement of a plurality of bag sets. Each air bag set is provided therein with a first air bag which has a second air bag therein, so that the first air bag is divided into two air chambers A, B. When the air chambers A, B are inflated or deflated simultaneously, the first air bag is inflated or deflated twice as much to increase ventilation effect. When the first air bag is deflated automatically because of a power loss or machine failure, the second air bag keeps the patient comfortable.
2. Description of the Prior Art
As shown in FIG. 1 and 2, conventionally, the body of the patient lying on a bed for a long period can be provided with adequate ventilation for the skin of his body by alternately changing contact points of his body with an air bed to avoid obtaining pressure sores and decubitus ulcers. In the conventional air bed, a plurality of air bags 10 are arranged on a hard plate. The air bags 10 of the odd numbers and those of the even numbers have their intake (discharge) holes 11 connected to an air pump. A switch is used to control simultaneous or alternate discharge or intake of the air bags 10 of the odd numbers and of the even numbers to alternate the contact points of the patient to avoid obtaining pressure sores and decubitus ulcers.
However, once there is a power loss or machine failure, air in the air bags will be released gradually, so that the body of the patient will come into contact with the hard plate directly, and the patient will feel uncomfortable.
Hence an "AIR BED WITH ALTERNATELY RAISED/LOWERED UNITED AIR BAGS" (patent application No. 84204580 filed in Taiwan, R.O.C.) as depicted in FIG. 1 was provided in the markets which is an improvement directed to the above stated defect. This air bed is similarly provided with a plurality of air bag sets 20, wherein, each air bag set 20 is divided by a transverse diaphragm 21 into an upper air chamber 22 and a lower air chamber 23. Air in the lower air chamber 23 is kept fully inflated, while the upper air chamber 22 is alternately raised or lowered by input and extraction of air by a pump. Once there is a power loss or machine failure, the inflated condition in the lower air chamber 23 prevents the patient lying on the air bed from direct contact with the hard plate.
However, only the upper air chamber 22 of the air bag set 20 has the function of air inflation/deflation, so that the vertical range that it is raised or lowered equals the height of the upper air chamber 22; this means that, while the improved air bed can make the patient more comfortable when there is a power loss or machine failure, if it is an alternate inflation/deflation mode, the space available for ventilation can only be provided in the height of the upper air chamber 22. Thus, the possible effect of ventilation and heat sinking is much inferior to that of a conventional air bed, and is only half of the latter. A patient with inferior circulation of blood lying on the air bed may still get pressure sores and decubitus ulcers induced thereby.
Moreover, when there is a power loss or machine failure, air in the upper air chamber 22 will be discharged automatically and the surface of the air bed will be flattened (as is shown in FIG. 4). The patient lying on the air bed will directly contact the flattened air bed resulting in bad ventilation. If the power loss or machine failure can not be corrected, the patient may get pressure sores and decubitus ulcers.
Additionally, the conventional air bed and the above stated improved air bed have a common defect that, when the neighboring air bags are alternately inflated/deflated, the air bags being deflated are pressed by two neighbouring air bags in the state of inflation and thus are not lowered properly. This results in an overly small ventilation space. Therefore, the effect of ventilation and heat sinking is inferior.